June 27, 2014


A Shocking Fish Tale Surprises Evolutionary Biologists (NELL GREENFIELDBOYCE, June 26, 2014, NPR)

Scientists say it's amazing that evolution invented an organ for making electricity even once. But, in fact, evolution did it at least six separate times in completely different fish -- how is that possible?

Sussman and a bunch of other scientists wanted to know. So they analyzed all the genes of the electric eel, then also looked at gene activity in other electric fishes from unrelated families. What they discovered was, well, shocking.

"They're using the same genetic tools to build their electric organs in each lineage independently," says Jason Gallant, an electric fish specialist at Michigan State University, in East Lansing, who was part of the research team.

Again and again, evolution used the same set of about 30 genes.

"It seems like there are limited ways to build an electric organ," he says. "And that's sort of a surprising finding ... you wouldn't necessarily have expected that."

Others experts agree. "When I read this paper, I said, 'Yeah, that's cool, that's obvious.' The fact is, it wasn't that obvious," says Leonard Maler, who studies electric fish at the University of Ottawa.

Maler notes that to create an electric organ, many genetic changes have to happen -- and each one on its own wouldn't seem to be advantageous for the fish. For example, a muscle that loses its ability to contract is a pretty lousy muscle.

"You have to simultaneously co-evolve genes that do very many different things in some kind of directed manner. It [can't just] be random," says Maler. 
Posted by at June 27, 2014 5:06 PM
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